The Sequencing Batch Reactor (SBR) process is a modification of the conventional activated sludge process employing a fill, treat and draw sequence.
In the SBR process, raw waste water is transferred to a reactor during a fill and react cycle. Air is introduced into the tank during this cycle to aerobically oxydize carbon and nitrogen in the form of biochemical oxygen demand (BOD) and total Kjeldahl nitrogen (TKN). When the tank fills to a predetermined high level, the raw sewage influent shuts off, air may be shut off, and the tank contents begin a react only cycle to ensure that effluent discharge requirements are obtained. Following the react cycle, the mixed liquor is allowed to settle. Clarified supernatant (effluent) occupies the upper half of the tank volume. After this settle cycle, a decant cycle begins, during which time a pump is used to draw off and discharge the treated effluent. Following effluent discharge, the apparatus enters an idle phase until the fill and react cycle begins again to repeat the entire process.